Devices known generally as lawn, garden or pavement blowers have been aiding domestic and commercial yard maintenance for many years. Although there are a number of brands and models on the market, the value of any given blower depends on only a few characteristics, the most important of which are price, weight and of course how effectively they propel leaf litter and debris. These three characteristics are related. The more powerful the blower motor, the heavier and more expensive an individual device will tend to be. The weight of the unit can become an important factor after a prolonged period of use. Therefore, it is desirable to maximize air flow efficiency so that a blower with a given motor can perform the greatest amount of work for its weight and cost.
High air velocity is generally viewed as desirable in yard and pavement sweeping applications. However, in order to maximize air velocity, the flow of air must be concentrated by a nozzle having, for example, a smaller, generally circular opening. While a concentrator nozzle has had the desired effect of increasing air velocity, the resulting air jet is narrow and thus does not efficiently sweep or clear a wide area, and, in fact, creates turbulent air flows in the vicinity that tends to blow leaves back at the operator. To provide a wider pattern of air generally parallel to the ground, the nozzle opening is made wider a direction parallel to the ground, and narrower in a direction perpendicular to the ground. In other words, the opening is formed in the shape of a slot. However, a slot shaped opening is comparatively inefficient and causes a substantial loss of velocity.